Taming all the trees.

dict_traverser.py

def traverse_dict(node, leaf_fn, node_fn=lambda v, path: None, path=tuple()):
    for k, v in node.iteritems():
        current_path = path + tuple([k])
        if isinstance(v, dict):
            node_fn(v, current_path)
            traverse_dict(v, leaf_fn, node_fn, current_path)
        elif isinstance(v, list):
            current_path = current_path + tuple(["[*]"])
            for i in v:
                if isinstance(i, dict):
                    node_fn(i, current_path)
                    traverse_dict(i, leaf_fn, node_fn, current_path)
                else:
                    leaf_fn(i, current_path)
        else:
            leaf_fn(v, current_path)

test_dict_traverser.py

def test_traverse_dict_handles_dicts_as_values():
    d = {"a": {"bc": 0}}

    def test_fn(value, path):
        eq_(value, 0)
        eq_(path, ("a", "bc"))

    traverse_dict(d, test_fn)


def test_traverse_dict_handles_lists_of_dicts():
    d = {"a": [{"b": 1}, {"b": 2}]}

    def test_fn(value, path):
        assert(value == 1 or value == 2)
        eq_(path, ("a", "[*]", "b"))

    traverse_dict(d, test_fn)